/*
 * ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
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/*
 *
 *
 *
 *
 *
 * Written by Doug Lea and Josh Bloch with assistance from members of JCP
 * JSR-166 Expert Group and released to the public domain, as explained at
 * http://creativecommons.org/publicdomain/zero/1.0/
 */

package java.util;

/**
 * A {@link SortedMap} extended with navigation methods returning the
 * closest matches for given search targets. Methods
 * {@code lowerEntry}, {@code floorEntry}, {@code ceilingEntry},
 * and {@code higherEntry} return {@code Map.Entry} objects
 * associated with keys respectively less than, less than or equal,
 * greater than or equal, and greater than a given key, returning
 * {@code null} if there is no such key.  Similarly, methods
 * {@code lowerKey}, {@code floorKey}, {@code ceilingKey}, and
 * {@code higherKey} return only the associated keys. All of these
 * methods are designed for locating, not traversing entries.
 *
 * <p>A {@code NavigableMap} may be accessed and traversed in either
 * ascending or descending key order.  The {@code descendingMap}
 * method returns a view of the map with the senses of all relational
 * and directional methods inverted. The performance of ascending
 * operations and views is likely to be faster than that of descending
 * ones.  Methods {@code subMap}, {@code headMap},
 * and {@code tailMap} differ from the like-named {@code
 * SortedMap} methods in accepting additional arguments describing
 * whether lower and upper bounds are inclusive versus exclusive.
 * Submaps of any {@code NavigableMap} must implement the {@code
 * NavigableMap} interface.
 *
 * <p>This interface additionally defines methods {@code firstEntry},
 * {@code pollFirstEntry}, {@code lastEntry}, and
 * {@code pollLastEntry} that return and/or remove the least and
 * greatest mappings, if any exist, else returning {@code null}.
 *
 * <p>Implementations of entry-returning methods are expected to
 * return {@code Map.Entry} pairs representing snapshots of mappings
 * at the time they were produced, and thus generally do <em>not</em>
 * support the optional {@code Entry.setValue} method. Note however
 * that it is possible to change mappings in the associated map using
 * method {@code put}.
 *
 * <p>Methods
 * {@link #subMap(Object, Object) subMap(K, K)},
 * {@link #headMap(Object) headMap(K)}, and
 * {@link #tailMap(Object) tailMap(K)}
 * are specified to return {@code SortedMap} to allow existing
 * implementations of {@code SortedMap} to be compatibly retrofitted to
 * implement {@code NavigableMap}, but extensions and implementations
 * of this interface are encouraged to override these methods to return
 * {@code NavigableMap}.  Similarly,
 * {@link #keySet()} can be overriden to return {@code NavigableSet}.
 *
 * <p>This interface is a member of the
 * <a href="{@docRoot}/../technotes/guides/collections/index.html">
 * Java Collections Framework</a>.
 *
 * @param <K> the type of keys maintained by this map
 * @param <V> the type of mapped values
 * @author Doug Lea
 * @author Josh Bloch
 * @since 1.6
 */
public interface NavigableMap<K, V> extends SortedMap<K, V> {

  /**
   * Returns a key-value mapping associated with the greatest key
   * strictly less than the given key, or {@code null} if there is
   * no such key.
   *
   * @param key the key
   * @return an entry with the greatest key less than {@code key}, or {@code null} if there is no
   * such key
   * @throws ClassCastException if the specified key cannot be compared with the keys currently in
   * the map
   * @throws NullPointerException if the specified key is null and this map does not permit null
   * keys
   */
  Map.Entry<K, V> lowerEntry(K key);

  /**
   * Returns the greatest key strictly less than the given key, or
   * {@code null} if there is no such key.
   *
   * @param key the key
   * @return the greatest key less than {@code key}, or {@code null} if there is no such key
   * @throws ClassCastException if the specified key cannot be compared with the keys currently in
   * the map
   * @throws NullPointerException if the specified key is null and this map does not permit null
   * keys
   */
  K lowerKey(K key);

  /**
   * Returns a key-value mapping associated with the greatest key
   * less than or equal to the given key, or {@code null} if there
   * is no such key.
   *
   * @param key the key
   * @return an entry with the greatest key less than or equal to {@code key}, or {@code null} if
   * there is no such key
   * @throws ClassCastException if the specified key cannot be compared with the keys currently in
   * the map
   * @throws NullPointerException if the specified key is null and this map does not permit null
   * keys
   */
  Map.Entry<K, V> floorEntry(K key);

  /**
   * Returns the greatest key less than or equal to the given key,
   * or {@code null} if there is no such key.
   *
   * @param key the key
   * @return the greatest key less than or equal to {@code key}, or {@code null} if there is no such
   * key
   * @throws ClassCastException if the specified key cannot be compared with the keys currently in
   * the map
   * @throws NullPointerException if the specified key is null and this map does not permit null
   * keys
   */
  K floorKey(K key);

  /**
   * Returns a key-value mapping associated with the least key
   * greater than or equal to the given key, or {@code null} if
   * there is no such key.
   *
   * @param key the key
   * @return an entry with the least key greater than or equal to {@code key}, or {@code null} if
   * there is no such key
   * @throws ClassCastException if the specified key cannot be compared with the keys currently in
   * the map
   * @throws NullPointerException if the specified key is null and this map does not permit null
   * keys
   */
  Map.Entry<K, V> ceilingEntry(K key);

  /**
   * Returns the least key greater than or equal to the given key,
   * or {@code null} if there is no such key.
   *
   * @param key the key
   * @return the least key greater than or equal to {@code key}, or {@code null} if there is no such
   * key
   * @throws ClassCastException if the specified key cannot be compared with the keys currently in
   * the map
   * @throws NullPointerException if the specified key is null and this map does not permit null
   * keys
   */
  K ceilingKey(K key);

  /**
   * Returns a key-value mapping associated with the least key
   * strictly greater than the given key, or {@code null} if there
   * is no such key.
   *
   * @param key the key
   * @return an entry with the least key greater than {@code key}, or {@code null} if there is no
   * such key
   * @throws ClassCastException if the specified key cannot be compared with the keys currently in
   * the map
   * @throws NullPointerException if the specified key is null and this map does not permit null
   * keys
   */
  Map.Entry<K, V> higherEntry(K key);

  /**
   * Returns the least key strictly greater than the given key, or
   * {@code null} if there is no such key.
   *
   * @param key the key
   * @return the least key greater than {@code key}, or {@code null} if there is no such key
   * @throws ClassCastException if the specified key cannot be compared with the keys currently in
   * the map
   * @throws NullPointerException if the specified key is null and this map does not permit null
   * keys
   */
  K higherKey(K key);

  /**
   * Returns a key-value mapping associated with the least
   * key in this map, or {@code null} if the map is empty.
   *
   * @return an entry with the least key, or {@code null} if this map is empty
   */
  Map.Entry<K, V> firstEntry();

  /**
   * Returns a key-value mapping associated with the greatest
   * key in this map, or {@code null} if the map is empty.
   *
   * @return an entry with the greatest key, or {@code null} if this map is empty
   */
  Map.Entry<K, V> lastEntry();

  /**
   * Removes and returns a key-value mapping associated with
   * the least key in this map, or {@code null} if the map is empty.
   *
   * @return the removed first entry of this map, or {@code null} if this map is empty
   */
  Map.Entry<K, V> pollFirstEntry();

  /**
   * Removes and returns a key-value mapping associated with
   * the greatest key in this map, or {@code null} if the map is empty.
   *
   * @return the removed last entry of this map, or {@code null} if this map is empty
   */
  Map.Entry<K, V> pollLastEntry();

  /**
   * Returns a reverse order view of the mappings contained in this map.
   * The descending map is backed by this map, so changes to the map are
   * reflected in the descending map, and vice-versa.  If either map is
   * modified while an iteration over a collection view of either map
   * is in progress (except through the iterator's own {@code remove}
   * operation), the results of the iteration are undefined.
   *
   * <p>The returned map has an ordering equivalent to
   * <tt>{@link Collections#reverseOrder(Comparator) Collections.reverseOrder}(comparator())</tt>.
   * The expression {@code m.descendingMap().descendingMap()} returns a
   * view of {@code m} essentially equivalent to {@code m}.
   *
   * @return a reverse order view of this map
   */
  NavigableMap<K, V> descendingMap();

  /**
   * Returns a {@link NavigableSet} view of the keys contained in this map.
   * The set's iterator returns the keys in ascending order.
   * The set is backed by the map, so changes to the map are reflected in
   * the set, and vice-versa.  If the map is modified while an iteration
   * over the set is in progress (except through the iterator's own {@code
   * remove} operation), the results of the iteration are undefined.  The
   * set supports element removal, which removes the corresponding mapping
   * from the map, via the {@code Iterator.remove}, {@code Set.remove},
   * {@code removeAll}, {@code retainAll}, and {@code clear} operations.
   * It does not support the {@code add} or {@code addAll} operations.
   *
   * @return a navigable set view of the keys in this map
   */
  NavigableSet<K> navigableKeySet();

  /**
   * Returns a reverse order {@link NavigableSet} view of the keys contained in this map.
   * The set's iterator returns the keys in descending order.
   * The set is backed by the map, so changes to the map are reflected in
   * the set, and vice-versa.  If the map is modified while an iteration
   * over the set is in progress (except through the iterator's own {@code
   * remove} operation), the results of the iteration are undefined.  The
   * set supports element removal, which removes the corresponding mapping
   * from the map, via the {@code Iterator.remove}, {@code Set.remove},
   * {@code removeAll}, {@code retainAll}, and {@code clear} operations.
   * It does not support the {@code add} or {@code addAll} operations.
   *
   * @return a reverse order navigable set view of the keys in this map
   */
  NavigableSet<K> descendingKeySet();

  /**
   * Returns a view of the portion of this map whose keys range from
   * {@code fromKey} to {@code toKey}.  If {@code fromKey} and
   * {@code toKey} are equal, the returned map is empty unless
   * {@code fromInclusive} and {@code toInclusive} are both true.  The
   * returned map is backed by this map, so changes in the returned map are
   * reflected in this map, and vice-versa.  The returned map supports all
   * optional map operations that this map supports.
   *
   * <p>The returned map will throw an {@code IllegalArgumentException}
   * on an attempt to insert a key outside of its range, or to construct a
   * submap either of whose endpoints lie outside its range.
   *
   * @param fromKey low endpoint of the keys in the returned map
   * @param fromInclusive {@code true} if the low endpoint is to be included in the returned view
   * @param toKey high endpoint of the keys in the returned map
   * @param toInclusive {@code true} if the high endpoint is to be included in the returned view
   * @return a view of the portion of this map whose keys range from {@code fromKey} to {@code
   * toKey}
   * @throws ClassCastException if {@code fromKey} and {@code toKey} cannot be compared to one
   * another using this map's comparator (or, if the map has no comparator, using natural ordering).
   * Implementations may, but are not required to, throw this exception if {@code fromKey} or {@code
   * toKey} cannot be compared to keys currently in the map.
   * @throws NullPointerException if {@code fromKey} or {@code toKey} is null and this map does not
   * permit null keys
   * @throws IllegalArgumentException if {@code fromKey} is greater than {@code toKey}; or if this
   * map itself has a restricted range, and {@code fromKey} or {@code toKey} lies outside the bounds
   * of the range
   */
  NavigableMap<K, V> subMap(K fromKey, boolean fromInclusive,
      K toKey, boolean toInclusive);

  /**
   * Returns a view of the portion of this map whose keys are less than (or
   * equal to, if {@code inclusive} is true) {@code toKey}.  The returned
   * map is backed by this map, so changes in the returned map are reflected
   * in this map, and vice-versa.  The returned map supports all optional
   * map operations that this map supports.
   *
   * <p>The returned map will throw an {@code IllegalArgumentException}
   * on an attempt to insert a key outside its range.
   *
   * @param toKey high endpoint of the keys in the returned map
   * @param inclusive {@code true} if the high endpoint is to be included in the returned view
   * @return a view of the portion of this map whose keys are less than (or equal to, if {@code
   * inclusive} is true) {@code toKey}
   * @throws ClassCastException if {@code toKey} is not compatible with this map's comparator (or,
   * if the map has no comparator, if {@code toKey} does not implement {@link Comparable}).
   * Implementations may, but are not required to, throw this exception if {@code toKey} cannot be
   * compared to keys currently in the map.
   * @throws NullPointerException if {@code toKey} is null and this map does not permit null keys
   * @throws IllegalArgumentException if this map itself has a restricted range, and {@code toKey}
   * lies outside the bounds of the range
   */
  NavigableMap<K, V> headMap(K toKey, boolean inclusive);

  /**
   * Returns a view of the portion of this map whose keys are greater than (or
   * equal to, if {@code inclusive} is true) {@code fromKey}.  The returned
   * map is backed by this map, so changes in the returned map are reflected
   * in this map, and vice-versa.  The returned map supports all optional
   * map operations that this map supports.
   *
   * <p>The returned map will throw an {@code IllegalArgumentException}
   * on an attempt to insert a key outside its range.
   *
   * @param fromKey low endpoint of the keys in the returned map
   * @param inclusive {@code true} if the low endpoint is to be included in the returned view
   * @return a view of the portion of this map whose keys are greater than (or equal to, if {@code
   * inclusive} is true) {@code fromKey}
   * @throws ClassCastException if {@code fromKey} is not compatible with this map's comparator (or,
   * if the map has no comparator, if {@code fromKey} does not implement {@link Comparable}).
   * Implementations may, but are not required to, throw this exception if {@code fromKey} cannot be
   * compared to keys currently in the map.
   * @throws NullPointerException if {@code fromKey} is null and this map does not permit null keys
   * @throws IllegalArgumentException if this map itself has a restricted range, and {@code fromKey}
   * lies outside the bounds of the range
   */
  NavigableMap<K, V> tailMap(K fromKey, boolean inclusive);

  /**
   * {@inheritDoc}
   *
   * <p>Equivalent to {@code subMap(fromKey, true, toKey, false)}.
   *
   * @throws ClassCastException {@inheritDoc}
   * @throws NullPointerException {@inheritDoc}
   * @throws IllegalArgumentException {@inheritDoc}
   */
  SortedMap<K, V> subMap(K fromKey, K toKey);

  /**
   * {@inheritDoc}
   *
   * <p>Equivalent to {@code headMap(toKey, false)}.
   *
   * @throws ClassCastException {@inheritDoc}
   * @throws NullPointerException {@inheritDoc}
   * @throws IllegalArgumentException {@inheritDoc}
   */
  SortedMap<K, V> headMap(K toKey);

  /**
   * {@inheritDoc}
   *
   * <p>Equivalent to {@code tailMap(fromKey, true)}.
   *
   * @throws ClassCastException {@inheritDoc}
   * @throws NullPointerException {@inheritDoc}
   * @throws IllegalArgumentException {@inheritDoc}
   */
  SortedMap<K, V> tailMap(K fromKey);
}
